/*
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.pom.event;

import com.intellij.pom.PomModel;
import com.intellij.pom.PomModelAspect;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.*;

public class PomModelEvent extends EventObject {
    private Map<PomModelAspect, PomChangeSet> myChangeSets;

    public PomModelEvent(PomModel source) {
        super(source);
    }

    @NotNull
    public Set<PomModelAspect> getChangedAspects() {
        if (myChangeSets != null) {
            return myChangeSets.keySet();
        } else {
            return Collections.emptySet();
        }
    }

    public void registerChangeSet(PomModelAspect aspect, PomChangeSet set) {
        if (myChangeSets == null) {
            myChangeSets = new HashMap<>();
        }
        if (set == null) {
            myChangeSets.remove(aspect);
        } else {
            myChangeSets.put(aspect, set);
        }
    }

    public <T extends PomChangeSet> T registerChangeSetIfAbsent(PomModelAspect aspect, @NotNull T set) {
        final PomChangeSet oldSet = getChangeSet(aspect);
        if (oldSet != null) return (T) oldSet;

        registerChangeSet(aspect, set);
        return set;
    }


    @Nullable
    public PomChangeSet getChangeSet(PomModelAspect aspect) {
        if (myChangeSets == null) return null;
        return myChangeSets.get(aspect);
    }

    public void merge(@NotNull PomModelEvent event) {
        if (event.myChangeSets == null) return;
        if (myChangeSets == null) {
            myChangeSets = new HashMap<>(event.myChangeSets);
            return;
        }
        for (final Map.Entry<PomModelAspect, PomChangeSet> entry : event.myChangeSets.entrySet()) {
            final PomModelAspect aspect = entry.getKey();
            final PomChangeSet pomChangeSet = myChangeSets.get(aspect);
            if (pomChangeSet != null) {
                pomChangeSet.merge(entry.getValue());
            } else {
                myChangeSets.put(aspect, entry.getValue());
            }
        }
    }


    @Override
    public PomModel getSource() {
        return (PomModel) super.getSource();
    }

    public void beforeNestedTransaction() {
        if (myChangeSets != null) {
            for (PomChangeSet changeSet : myChangeSets.values()) {
                changeSet.beforeNestedTransaction();
            }
        }
    }
}
